The purpose of this study is to simulate the impact of food intake on drug release and absorption in vivo using in vitro dissolution method in fed condition and to establish in vitro/in vivo correlation that could predict the bioavailability of drug instead of using difficult, time-consuming and expensive in vivo bioequivalence studies. The dissolution of Entecavir (BaracludeTM), model compound of BCS class Ⅲ, was studied using the basket apparatus and paddle apparatus based on a method described in USP. The dissolution media of fed condition maintained at 37.0±0.5℃. Rotation speed of 50, 75 and 100 rpm was used. For in vivo bioavailability test in fed condition, Entecavir was orally administrated with meal in the beagle dogs and assayed the blood concentration of entecavir by LC MS/MS. The previous study, absorption of BaracludeTM was altered with food intake, as evidenced by a decrease in Cmax 63%, AUC0-t of 22% and delay in Tmax. It shows that BaracludeTM was dissolved more than 75% under fed condition with paddle method at all of rotation speeds. But it shows 10.4%, 56.2% and 67.4% at rotation speed of 50, 75 and 100 rpm under fed condition with basket method. As a result of in vivo beagle dog test, oral exposal of Fast was higher than that of Slow in proportion of in vitro dissolution rate.